Question 17130: Please help! I need to graph both equations of each system in the same coordinate plane. Then estimate the solution (that is, the coordinates of the point of intersection) to the nearest half unit. y = -x + 3 and y = x - 4 Please explain to me how I would go about doing this.
Answer by rapaljer(4671)   (Show Source):
You can put this solution on YOUR website! Graph the lines. If you need help with this, then see my recently posted Lesson Plan called Graphing and Slope of a Line.
Remember that you have TWO separate lines to graph. Each of those lines has a y-intercept, which is the point on the y-axis where the graph crosses and also it is the point where x=0. That's the first point to graph.
Locate the y-intercept for the first line, which is y=-x+3, where the y intercept is 3. So go up three units on the y axis, and put the first point. Next, the slope of the line is the coefficient of x, which is -1. This slope of -1 can be written as  , which means that you have a rise of -1 (like DOWN 1), and over (to the RIGHT) 1 unit. Start with your pencil on the y intercept, and from that point, move DOWN 1, and right 1, and put another point. Then connect the points, and you have the first line.
For the second line y = x-4, the yintercept is -4, and the slope is 1 which means that m= 1/1. Start with the y intercept by going DOWN 4 on the y axis and put a point. With your pencil on this point, and move UP 1 and to the RIGHT 1 unit, and put another point. Connect these points and you will get the line.
See if these graphs agree with this:
From looking at the graph, it looks like the two graphs intersect at about halfway between 3 and 4. Let's take a guess at x = 3.5. Y is between -1 and 0. Guess that y is about -.5. The solution rounded to the nearest half would be (3.5, -.5).
R^2 at SCC
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